Hearing loss is the second most common service-related disability among Veterans, and together with the progressive effects associated with aging on the auditory system, presents an important challenge for effective Veteran care. Auditory rehabilitation commonly includes hearing aids as a means to improve audibility and allow access to important cues for accurate speech perception, which, in turn, promotes successful communication and engagement in the psychosocial aspects of life. In addition to immediate audibility improvements introduced by amplifying sound with a hearing aid, amplification has the potential to have long-term effects on higher level auditory processing abilities, such as cognition or other abilities required for complex listening tasks. Long-term effects of amplification, also known as acclimatization effects, are not well understood relative to more immediate audibility-related effects. A behavioral and physiological examination of the effects that are associated with hearing aid use may help to clarify the positive impacts of amplification as a rehabilitation approach. This research program sets out to establish both the immediate and long-term effects of hearing aid amplification using electrophysiological and behavioral outcome measures. The combination of these measures may lead to important discoveries into understanding the successful versus the unsuccessful hearing aid user. For example, by comparing and contrasting the effects of hearing aids on different measures we will understand more about the physiology that underlies satisfaction and success with amplification. Use of both behavioral and physiological data will provide a more detailed view of individual differences that contribute to receiving benefit from a hearing aid and may lead to more individualized treatment of hearing loss.